The present invention relates to methods and apparatus for measuring and inspecting articles of manufacture, and pertains particularly to an improved method and apparatus for noncontact measuring and inspecting of articles of complex configurations.
It is frequently necessary to carefully inspect the configuration of manufactured parts in order to insure proper fit in the assembly process. Many different approaches have been proposed in the past for providing efficient and accurate systems for such measurement and inspection of such articles. While many such devices have been developed and provide many improvements, they are still deficient in many respects.
One area of particular concern for which the present invention has been developed is that of measuring bent tubing, such as fuel, hydraulic and other fluid carrying tubing. In the inspection of such articles, it is necessary to measure in three dimensions the axis of several straight portions in order to define the length of the straight portions, the angle of the bend between adjacent straight portions, and the angle of the plane of one bend with respect to the plane of another bend.
In my prior U.S. Pat. No. 3,944,798, entitled "Method and Apparatus for Measuring Direction", which is incorporated herein by reference, I provide a significantly improved device for measuring such articles of manufacturing. The apparatus disclosed and claimed in my prior patent is directed to a five axis articulated probe, having a working head that may be oriented in three dimensions so as to align itself with a straight portion of the tube. This arrangement requires actual contact of the working head with the article of manufacture, and permits measurement of the vector that is parallel to the tube axis to be made with a single operation. With this apparatus, however, the article being measured must be clamped to a support, and then contacted with the measuring instrument, at least once for each straight portion, in order to obtain the desired information. This operation is time consuming and may be ineffective, particularly for non-conductive or coated articles.
In my more recent U.S. Pat. No. 4,122,525, entitled "Method and Apparatus for Profile Scanning", which is incorporated herein by reference, I disclose a further improvement in inspection apparatus, wherein an object is scanned by moving a scanning beam across the object in a scan pattern, relatively moving the object and the pattern, and generating signals at collectively defined points of intersection of the beam scan pattern with a boundary of the object. The major drawback of this apparatus is that it is complex and has many moving parts.
U.S. Pat. No. 4,778,274, entitled "Noncontact Measuring Device for Cylindrical, Elongated Objects Bent Into Three-Dimensional Shapes", granted Oct. 18, 1988 to Yogo, discloses another approach to the measuring and inspecting of such articles. This apparatus, however, provides a scanning head, which must be tracked by complex mechanisms along the length of the article.
The present invention was devised to provide an apparatus that overcomes the above problems of the prior art.